MIL-STD-1411B
5.4.2.5 Charging cylinders with fuel gas mixtures. Fuel gas mixtures are supplied to the government as proprietary products. Government cylinders are provided for filling to nominal weights, such as 7.5 pounds for portable applications or 70 pounds for stationary or mobile applications. These gases are an inhibited mixture of gases that are readily liquefied under pressure and should be handled like liquefied petroleum in charging. The fuel gas cylinder shall be weighed to determine its tare weight, which shall then be recorded. The cylinder is charged
to its authorized weight with liquefied commodity. The net product weight is determined to be the gross weight less the recorded tare weight.
5.4.2.6 Charging carbon dioxide cylinders. Carbon dioxide cylinders arrive at the charging station with residual pressure from previous filling or contain one atmosphere of gas from drying at 180 °F. When a cylinder contains residual carbon dioxide, it shall be bled down to one atmosphere of pressure. Connection shall be made with the carbon dioxide supply manifold and charging shall follow. When a cylinder has been dried at 180 °F and closed, a negative pressure will be developed on cooling. Connect the valve outlet to the carbon dioxide supply manifold with a gas-tight seal before the cylinder valve is opened to prevent the contamination of the cylinder with atmospheric moisture. Carbon dioxide should be purchased by weight. The net product weight of carbon dioxide supplied in each cylinder is the difference between the filled weight and the unfilled weight of the cylinder. Carbon dioxide cylinders shall never be charged above 68 percent filling density.
5.4.2.7 Charging sulfur hexafluoride cylinders. At the charging station, sulfur hexafluoride cylinders will be exhausted, devalved (see 5.3.2.1), purged with air, internally inspected, and cleaned to the base metal in accordance with 5.3.5 (c) and (d). Each cylinder may be charged to a filling density not greater than 110 percent times the water capacity of the cylinder. Each cylinder shall be weighed and recorded for tare weight. The cylinder shall be evacuated to an absolute pressure of 3 inches of mercury and maintained for a minimum of 2 minutes before filling begins. The cylinder shall be charged with hexafluoride to its authorized weight. The net product weight is determined to be the gross weight less the recorded tare weight.
5.4.3 Charging cylinders with acetylene. An acetylene cylinder at charging will ordinarily have a residual amount of acetylene dissolved in its acetone carrier and will have a heavier base weight than its marked tare weight, or cylinders devalved for inspection or acetone adjustment will have a base weight corresponding to the tare weight. Base weights shall be recorded and the cylinder shall be connected to the acetylene manifold. A given source of acetylene in cubic feet capacity per hour must be mated with a bank of cylinders capable of absorbing all the acetylene generated. Differential conditions can be varied at higher pressure (400 psig maximum) or at lower temperature (cooling closets) until a cylinder settled pressure of
250 psig at 70 °F or equivalent is achieved. Weigh the charged cylinder. With the base weight, calculate the quantity of the dissolved gas by weight and its equivalent cubic footage using the conversion factor of 14.7 cubic feet of acetylene per pound of gas weight. Record the number of cubic feet required to charge the cylinder. The dissolved weight of acetylene shall never exceed a cylinder's capacity in cubic feet divided by the conversion factor.
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